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Toxicity to aquatic algae and cyanobacteria

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Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
GLP compliance:
yes (incl. QA statement)
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source (i.e. manufacturer or supplier) and lot/batch number of test material: Batch no.: 27762-120, source: Sigma Aldrich Co. Ltd
- Purity, including information on contaminants, isomers, etc.: 99.20%

Analytical monitoring:
yes
Details on sampling:
- Concentrations: Water samples were taken from the control (replicates R1 - R3 pooled) and the 100 mg/l test group (replicates R1 - R3 and ~ - ~ pooled) at 0 and 72 hours for quantitative analysis..
- Sample storage conditions before analysis: Duplicate samples were taken at each occasion and stored frozen (approximately -20°C) for further analysis if necessary
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: An amount of test material (200 mg) was readily dissolved in culture medium and the volume adjusted to 1 litre to give a 200 mg/l stock solution. An aliquot (500 ml) of this stock solution was mixed with algal suspension (500 ml) to give the required test concentration of 100 mg/l.
- Controls: pure medium
Test organisms (species):
Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Common name: Pseudokirchneriella subcapitata
- Strain: CCAP 278/4
- Source (laboratory, culture collection): from the Culture Collection of Algae and Protozoa (CCAP), Institute of Freshwater Ecology, The Ferry House, Far Sawrey, Ambleside, Cumbria.
- Method of cultivation: The culture was maintained in the laboratory at a temperature of 21 ± 1°C under continuous illumination (intensity approximately 7000 lux) and constant aeration.

Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Test temperature:
24 ± 1°C
pH:
at the start: 57.5
at the end: 8.5 - 8.7
Nominal and measured concentrations:
nominal: control and 100 mg/L
measured: control and 96 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: conical flasks
- Type (delete if not applicable): closed with polyurethane foam bungs
- Material, size, headspace, fill volume: glas, fill volume: 250 mL. test medium volume: 100 mL
- Aeration: no
- Initial cells density: 10000 cells/mL
- Control end cells density: 1.46E+06
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 3

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Intervals of water quality measurement: The pH of each control and test flask was determined at initiation of the test and after 72 hours exposure. Tue temperature within the incubator was recorded daily.

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: only at the start to 7.5
- Light intensity and quality: continuous illumination (intensity approximately 7000 lux)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: [counting chamber; electronic particle counter; fluorimeter; spectrophotometer; colorimeter] Coulter Multisizer Particle Counter

TEST CONCENTRATIONS
- Range finding study : yes
- Test concentrations: 1.0, 10 and 100 mg/l
- Results used to determine the conditions for the definitive study: The results showed no effect on growth at the test concentrations of 1.0, 10 and 100 mg/l.

CULTURING APPARATUS
-Details on culturing apparatus used: INFORS Multitron Version 2 incubator, constantly shaken at approximately 150 rpm for 72 hours.
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate

Table 1. Cell Densities and pH Values in the Definitive Test

Nominal concentration [mg/L]

pH

Cell Densities [cells/mL]

 

 

 

pH

 

0 h

0 h

24 h

48 h

72 h

72 h

Control

R1

7.5

9.42E+o3

7.59E+o4

3.31E+05

1.41E+o6

8.7

 

R2

7.5

9.00E+03

5.84E+04

3.31E+05

1.59E+o6

8.7

 

R3

7.5

9.33E+o3

6.82E+04

3.32E+05

1.38E+o6

8.7

 

Mean

 

9.25E+o3

6.75E+04

3.32E+05

1.46E+o6

 

 

 

 

 

 

 

 

 

100

R1

7.5

8.82E+03

7.25E+04

3.33E+05

1.74E+06

8.6

 

R2

7.5

8.60E+03

6.85E+04

3.38E+05

1.72E+06

8.6

 

R3

7.5

8.47E+03

6.41E+04

3.26E+05

1.62E+06

8.6

 

R4

7.5

8.37E+03

6.35E+04

3.26E+05

1.37E+06

8.6

 

R5

7.5

8.51E+03

7.19E+04

3.23E+05

1.44E+06

8.6

 

R6

7.5

8.52E+03

6.37E+04

3.26E+05

1.85E+06

8.5

 

Mean

 

8.55E+03

6.74E+04

3.29E+05

1.62E+06

 

 

Table 2. Results of the analytical measurement of test solutions

Sample

Nominal Concentration [mg/L]

Concentration Found [mg/L]

Expressed as a Percent of the Nominal Concentrations [%]

0 Hours

Control R1-R3

<LOQ

-

 

100 R1-R3

89.2

89

 

100 R1-R6

102

102

 

 

 

 

72 Hours

Control R1-R3

<LOQ

-

 

100 R1-R3

92.1

92

 

100 R1-R6

100

100

For the test to be valid, the following performance criteria should be met:

1)      The biomass in the control cultures should have increased exponentially by a factor of at least 16 within the 72-hour test period - Fulfilled (158)

2)     The mean coefficient of variation for section-by-section specific growth rates (days 0-1, 1-2 and 2-3, for 72-hour tests) in the control cultures must not exceed 35% - Fulfilled (16%)

3)     The coefficient of variation of average specific growth rates during the whole test period in replicate control cultures must not exceed 7% in tests with Pseudokirchneriella subcapitata and Desmodesmus subspicatus - Fulfilled (2)

Validity criteria fulfilled:
yes
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
1. SOFTWARE
Estimation Programs Interface (EPI) Suite for Microsoft Windows, v4.11 (US EPA, 2012)

2. MODEL (incl. version number)
ECOSAR v2.00

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
See section 'Test Material'.

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
See attached QMRF.

5. APPLICABILITY DOMAIN
See attached QPRF.

6. ADEQUACY OF THE RESULT
- The model is scientifically valid (see attached QMRF).
- The model estimates the toxicity to aquatic organisms: Daphnids: 48-h EC50; this data can be used to support the assessment regarding the toxicity of a substance to
aquatic organisms (see also attached QPRF).
Qualifier:
no guideline followed
Principles of method if other than guideline:
ECOSAR v2.00: Estimation of acute and chronic toxicity to green algae for chemical class "Neutral Organic SAR (Baseline Toxicity)"
GLP compliance:
no
Test organisms (species):
other: green algae
Water media type:
freshwater
Total exposure duration:
96 h
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
20 518 mg/L
Nominal / measured:
estimated
Conc. based on:
act. ingr.
Basis for effect:
not specified
Remarks on result:
other: ECOSAR chemical class: "Neutral Organic SAR (Baseline Toxicity)"; The substance is in the applicability domain of the model.
Dose descriptor:
other: Chronic Value (ChV)
Effect conc.:
2 486 mg/L
Nominal / measured:
estimated
Conc. based on:
act. ingr.
Basis for effect:
not specified
Remarks on result:
other: ECOSAR chemical class: "Neutral Organic SAR (Baseline Toxicity)"; The substance is in the applicability domain of the model.
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
1. SOFTWARE
Estimation Programs Interface (EPI) Suite for Microsoft Windows, v4.11 (US EPA, 2012)

2. MODEL (incl. version number)
ECOSAR v2.00

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
See section 'Test Material'.

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
See attached QMRF.

5. APPLICABILITY DOMAIN
See attached QPRF.

6. ADEQUACY OF THE RESULT
- The model is scientifically valid (see attached QMRF).
- The model estimates the toxicity to aquatic organisms: Daphnids: 48-h EC50; this data can be used to support the assessment regarding the toxicity of a substance to
aquatic organisms (see also attached QPRF).
Qualifier:
no guideline followed
Principles of method if other than guideline:
ECOSAR v2.00: Estimation of acute and chronic toxicity to green algae for chemical class "Neutral Organic SAR (Baseline Toxicity)"
GLP compliance:
no
Test organisms (species):
other: green algae
Water media type:
freshwater
Total exposure duration:
96 h
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
41 096 mg/L
Nominal / measured:
estimated
Conc. based on:
act. ingr.
Basis for effect:
not specified
Remarks on result:
other: ECOSAR chemical class: "Neutral Organic SAR (Baseline Toxicity)"; The substance is in the applicability domain of the model.
Dose descriptor:
other: Chronic Value (ChV)
Effect conc.:
4 706 mg/L
Nominal / measured:
estimated
Conc. based on:
act. ingr.
Basis for effect:
not specified
Remarks on result:
other: ECOSAR chemical class: "Neutral Organic SAR (Baseline Toxicity)"; The substance is in the applicability domain of the model.

Description of key information

From the available estimated data for constituents and its structurally similar it can be concluded that EC 907-131-0 is with high probability acutely not harmful to algae

Key value for chemical safety assessment

Additional information

QSAR-disclaimer

In Article 13 of Regulation (EC) No 1907/2006, it is laid down that information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI (of the same Regulation) are met.

According to Annex XI of Regulation (EC) No 1907/2006 (Q)SAR results can be used if (1) the scientific validity of the (Q)SAR model has been established, (2) the substance falls within the applicability domain of the (Q)SAR model, (3) the results are adequate for the purpose of classification and labelling and/or risk assessment and (4) adequate and reliable documentation of the applied method is provided.

For the assessment of the substance (Q)SAR results were used for the estimation of the toxicity to algae. The criteria listed in Annex XI of Regulation (EC) No 1907/2006 are considered to be adequately fulfilled and therefore the endpoint(s) sufficiently covered and suitable for risk assessment.

Assessment

2,2'-(ethylenedioxy)diethanol 3,6,9-trioxaundecane-1,11-diol (EC 907-131-0) is a multi-constituent substance. The main constituents of EC 907-131-0 are triethylene glycol (TGE, CAS 112-27-6, 10-80% w/w) and tetraethylene glycol (Tetra-EG, CAS 112-60-7, 10-80% w/w). Since no data on the toxicity to aquatic organisms of the reaction mass of 2,2'-(ethylenedioxy)diethanol 3,6,9-trioxaundecane-1,11-diol are available, the assessment is based on the available data for the main components triethylene glycol (CAS 112-27-6) and tetraethylene glycol (112-60-7).

Since no data on the toxicity for aquatic algae are available for main constituents the read.-across approach was performed. This read-across approach consists of the available experimental data for the structurally similar substance pentaethylene glycol (CAS 4792-15-8).

The key study according to OECD guideline 201 is available for pentaethylene glycol. In this study the green algae Pseudokirchnerella subcapitata was exposed for 72 hours in a limit test with a test concentration of 100 mg/L. No effects on the growth rate of the algae were determined (Mead & McKenzie, 2003 – cited in OECD SIDS, 2004).

This result is supported with the estimated values, which were derived for constituents from a valid QSAR model (ECOSAR v2.0; BASF SE, 2022). The 72 -h EC50 for CAS 112-27-6 was predicted to be 20518 mg/L, while the 72-h EC50 value for CAS 112-60-7 was estimated to be 41096 mg/L. The calculated chronic values (ChV) for CAS 112-27-6 and CAS 112-60-7 are 2486 and 4706 mg/L. Both substances were within the applicability domain of the model.

From the available estimated data for constituents and its structurally similar it can be concluded that EC 907-131-0 is with high probability acutely not harmful to algae